Does Sonoma County really have the tightest housing market in the United States, based on how quickly buyers are snapping up homes?

That’s what the Wall Street Journal reported on Monday, using data supplied by Realtor.com. But local real estate agents said the results, apparently based upon the company’s online listings, differ markedly from data supplied by the region’s multiple listing service.

“I just think there have to be hotter markets,” said Rick Laws, vice president in Santa Rosa for Pacific Union International and the producer of The Press Democrat’s monthly housing report. He acknowledged there isn’t an easy way to answer such questions but still found the Realtor.com results “hard to believe.”

The Journal on Monday reported that homes listed for sale in the Santa Rosa metropolitan area, which encompasses all of Sonoma County, in June remained on the market a median time of just 24 days. That was the shortest period for any U.S. metro area, according to Realtor.com.

The county previously has made the Realtor.com list for hottest housing markets. In March, it ranked fifth.

A number of California communities were close behind Sonoma County in the June rankings. In both San Jose and Vallejo, the median time on market for listed homes was 26 days. It was 27 days for the San Francisco-Oakland area and 29 days for both Sacramento and Modesto.

Realtor.com was unable Tuesday to provide a response to inquiries about its methodology. But its website suggested the data for the Santa Rosa metro area was based on 497 listings, out of a total of 1.8 million listings across its database.

In comparison, Laws said, the region’s multiple listing service reported a much larger sample, a total of 1,436 properties that were listed for sale in Sonoma County in June. That may help explain the county’s rising ranking with Realtor.com, Laws said, because a smaller sample could mean greater volatility from month to month.

Mike Kelly, an agent with Keller Williams in Santa Rosa, pointed out that the Realtor.com data put the median price at $580,000 for a home in Sonoma County in June. That was considerably higher than The Press Democrat’s figure of $550,000 and caused Kelly to question whether the online company’s data was truly representative of the county market.

“That could be a totally different animal,” said Kelly, who for years has hosted a weekly real estate show on KSRO radio. He said a number of Sonoma County real estate companies don’t place their listings on Realtor.com and other online sites.

Local agents and brokers this year have acknowledged that listed homes often stay on the market for a relatively brief period of time before their owners accept purchase offers from buyers. That helps explain why the inventory of available homes has been measured at two months or less for most of the past three years.

Nonetheless, some contend the current market isn’t as heated as in 2013, when the median price jumped 23 percent in one year. The June median price was 11 percent higher than a year earlier.

County real estate agents typically speak of days on market in terms of average numbers, not median figures, Law said.

In June, the available homes in Sonoma County were on the market an average of 49 days from initial listing until the signing of a contract, according to the listing service data. That amounted to a decrease of 18 percent from a year earlier — about half the size of the 35 percent decline reported by Realtor.com.

The median time on the market in June was 32 days, Laws said.

You can reach Staff Writer Robert Digitale at 521-5285 or robert.digitale@pressdemocrat.com. On Twitter @rdigit.